1. Field of Invention
The present disclosure relates to a silicone hydrogel composition. More particularly, the present disclosure relates to an UV-blocking silicone hydrogel composition and a silicone hydrogel contact lens containing the same.
2. Description of Related Art
Since contact lenses made from silicone hydrogel have high oxygen permeability, and allows sufficient oxygen directly through the lenses to the cornea, thereby providing sufficient oxygen to the cornea. As such, the silicone hydrogel contact lenses may less likely result in corneal hypoxia from lack of oxygen even after a prolonged wearing of contact lenses. Therefore, silicone hydrogel has become one of the preferable components for making contact lenses.
It is well known that sunlight may damage the human eye, especially in connection with the formation of cataracts and age-related macular degeneration which can lead to loss of vision. In the fraction of sunlight, the long wave and near ultraviolet (UVA and UVB) range are most concerned, which are characterized by wavelength of 285-380 nanometers (nm).
This band of ultraviolet radiation is known to damage human eyes by inducing chemical changes in lens and retina. To minimize the damage to eyes, eye protecting optical devices, especially sunglass, has been widely used for a long time. In the technical field of a medical device, a UV blocking compound in an intraocular lens is considered to provide the best UV blocking efficiency. These lenses were usually fabricated by copolymerizing polymerizable UV-blocking monomer with a lens formulation under heating condition. There were many efficient UV blocker monomers claimed useful in incorporated into a lens materials for UV protection especially based on benzotriazole or benzophenone mentioned in U.S. Pat. Nos. 4,528,311; 4,716,234; 4,719,248, 4,803,254.
However, it is difficult to manufacture a silicone hydrogel contact lens having a hydrophilic surface made of a hydrophobic silicon-based material, and it is extremely difficult to manufacture a silicone hydrogel contact lens having a hydrophilic surface made of a hydrophobic silicon-based material and a hydrophobic UV-blocking monomer. Therefore, how to manufacture a silicone hydrogel contact lens having good UV-blocking efficiency and good hydrophilicity is still an issue met in the art.